Speaker: Juliana Dias, NOAA/Boulder

Title: Are equatorial waves a practical source of deterministic sub-seasonal predictive skill?

Abstract: Propagating equatorial disturbances such as the Madden Julian Oscillation (MJO) and Convectively Coupled Equatorial waves (CCEW) are often seen as potentially useful for sub-seasonal predictions in the tropics and elsewhere via tropical-to-extratropical teleconnections. Quantifying this potential has been proven difficult in numerical weather prediction systems because tropical sub-seasonal variability tends to be poorly represented in such models. One possible exception is the European Centre for Medium-Range Weather Forecasts Integrated Forecast System (ECMWF), which has been recently shown to have much improved representation of sub-seasonal tropical variability. In this study, we use ECMWF reforecasts to investigate the predicted evolution of CCEW and the MJO and how they might relate to sub-seasonal practical and potential forecast skill.  It is shown that systematic model errors in the representation of their amplitude and propagation characteristics strongly limits their role as a deterministic pathway to improve sub-seasonal predictions. (Joint work by Juliana Dias, Maria Gehne and George Kiladis)

Bio: Juliana Dias is a research physical scientist at the Physical Sciences Laboratory (PSL) of the NOAA Earth System Research Laboratories in Boulder Colorado.  Her main interests include coupling between tropical convection and the large-scale atmospheric circulation, tropical-extratropical interactions, equatorial waves dynamics, and predictability of the atmosphere on daily to sub-seasonal time scales. Her work is focused on various aspects of tropical sub-seasonal variability,  tropical-extratropical interactions and on how those impact sub-seasonal predictions. Juliana's current projects include developing model diagnostics aimed at improving model's representation of tropical variability and understanding origins of tropical forecast errors as well as their impacts on extratropical subseasonal predictions.